Telemetry equipment for the two-dimensional or three-dimensional mapping of a volume

ABSTRACT

Telemetry equipment for two-dimensional or three-dimensional mapping of a space including a movable telemetry head including a first sensor for measuring a distance to a target within the space and a second sensor for measuring a distance to a third sensor; and a fixed unit for acquiring the position of the telemetry head in a fixed reference frame within the space, the fixed unit including the third sensor which performs the measurement of the distance between the second sensor and the third sensor.

RELATED APPLICATION

[0001] This is a continuation of International Application No.PCT/FR01/00482, with an international filing date of Feb. 19, 2001,which is based on French Patent Application No. 00/02038, filed Feb. 18,2000.

FIELD OF THE INVENTION

[0002] This invention relates to the field of telemetry and oftwo-dimensional or three-dimensional cartography.

BACKGROUND

[0003] The reference points of a plane or the acquisition of the volumeof an architectural or industrial space are generally determined bysurveyors using successive plotted reference points and tracing ofplanes from these reference points.

[0004] Plotting interior reference points encounters many obstacles. Itis slow and expensive if it is only performed manually because suchplotting must be performed by a skilled person, generally a surveyor. Itis also time-consuming if it is performed automatically with a devicebecause the device must record a considerable number of data (fine angleplotting laser telemetry), the computer processing of which can requiremany hours.

[0005] It is necessary to carry out a computer-based construction of theimage once the acquisition of points has been performed. Processing ofthe resultant image is time consuming (photogrammetric technique),complex and indeed not very reliable because of the difficulty ofautomatic interpretation of the results. Moreover, if these measurementsare performed by a device, the device must be positioned in an absolutereference frame to collect the measurements. The technique used bymotorized theodolites such as the double plotting technique according towhich the theodolite plots its own position from one measurement to thenext is precise, but time consuming.

[0006] Commonly used telemeters are elapsed time telemeters whichexhibit a precision of about 3 cm (1 cm on average over multiplemeasurements) which is not compatible with the precision required forinterior plotting.

[0007] French patent FR 2,630,539 has as its object processes forperforming surveys of envelope meter distances constituted of planesurfaces using a laser beam telemeter. The process of the prior artconsists of creating a means for the interior plotting, for themeasurement of meter distances over small distances in the buildinginterior and associating it with a computer-assisted design program toreproduce the envelopes and constitutive elements of a room in anydesired form. The telemeter is used to measure the meter distances ofthe polar coordinates of any cloud of points P taken on each surfaceconstituting the envelope from the same station S1. One then calculatesthe position of each plane, sphere, torus, cylinder or other simplesurface. Then, the intersection of all of the surfaces is taken two bytwo to define the edges of the volume under consideration.

[0008] Such a process is delicate to implement because it is totallyautomated, implying the taking into account of all of the geometricsituations which might be found in the field and the implementation ofcomplicated computer processing.

[0009] Also known is U.S. Pat. No. 5,337,149 which describes equipmentenabling creation of a computer-based model of a three-dimensionalobject of large dimensions as the data are acquired. This equipment ofthe prior art comprises a measurement device, a computer containing acomputer-assisted drafting program, a data transmission device and adisplay screen. The distance measurement device takes measurements froma stable location and which can be moved. The location of measuredpoints is calculated in relation to the distance of the measured pointand the orientation of the measurement device. The device and theprocess function in a manner such that the user is connected with thecomputer-assisted drafting program and uses the measurement device as aninput device to introduce the data into the program. Thus, the user cancreate a complete model of the object solely by taking the physicalmeasurements of an object or a space without any limitation of movementaround the object or the space, or through the space. It also describesa portable variant comprising an inertial unit.

[0010] Such equipment can only be used in a continuous space and doesnot enable acquisition of irregular volumes comprising masked zones, forexample, an apartment comprising multiple rooms separated by doors.Moreover, the portable variant unit only provides a differential signal,the exploitation of which requires powerful computing means and frequentrecalibrations.

[0011] Also known is U.S. Pat. No. 5,247,487, which describes a systemfor collecting measurements in space determining the position,orientation, form and/or operational characteristics of an environment.The system comprises a data-generating device and a modeling device. Thedata generated can then be transformed in a CADD (computer-assisteddesign and drafting) model of an existing or constructed environment, orused in another manner to obtain a three-dimensional topography of theenvironment.

[0012] This system employs a multiplicity of beacons positioned in theroom to be analyzed.

[0013] It would therefore be advantageous to resolve the drawbacks ofthe prior art by providing a solution that makes it possible to reducesubstantially the time required for the acquisition of usefulinformation. It would also be advantageous to provide a process andequipment making it possible to associate the person and the machine ina manner to only measure that which is necessary, thereby reducingmanual interventions to a minimum and optimizing the automatablefunctions.

SUMMARY OF THE INVENTION

[0014] This invention relates to telemetry equipment for two-dimensionalor three-dimensional mapping of a space including a movable telemetryhead including a first sensor for measuring a distance to a targetwithin the space and a second sensor for measuring a distance to a thirdsensor, and a fixed unit for acquiring the position of the telemetryhead in a fixed reference frame within the space, the fixed unitincluding the third sensor, which performs the measurement of thedistance between the second sensor and the third sensor.

[0015] This invention also relates to a telemetry process fortwo-dimensional or three-dimensional mapping of a space includingremotely acquiring a position and orientation of a laser telemeter(portable unit) in a fixed reference frame of a fixed unit within thespace by manual plotting with a portable tool including a sensoremitting a visible laser beam, and measuring the distance between thetelemeter and the fixed unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Better understanding of the invention will be obtained from thedescription below which makes reference to the attached drawings inwhich:

[0017]FIG. 1 represents a schematic view of an example of implementationof equipment according to aspects of the invention;

[0018]FIG. 2 represents a schematic view of an example of implementationof equipment according to a variant of implementation of the invention;

[0019]FIGS. 3 and 4 represent schematic views of two variants ofimplementation.

DETAILED DESCRIPTION

[0020] It will be appreciated that the following description is intendedto refer to specific embodiments of the invention selected forillustration in the drawings and is not intended to define or limit theinvention, other than in the appended claims.

[0021] In its most general sense, the invention relates to telemetryequipment for two-dimensional or three-dimensional mapping of a volume,the equipment comprising a telemetry head and a means for acquiring theposition of the measurement head in a fixed reference frame. Theequipment furthermore comprises an autonomous portable unit comprisingthe telemetry head and a fixed unit, the two units comprising means forremote acquisition of the position and orientation of the portable unitin the fixed reference frame.

[0022] The invention is, thus, composed of two complementary means:

[0023] a fixed station defining a reference point in the space to bemapped; and

[0024] a mobile piece of telemetric measurement equipment which is easyto handle and to move in nooks and crannies.

[0025] The fixed station establishes the position of the mobile unit inits fixed reference frame. The mobile unit acquires the position of apoint in space in relation to its mobile reference frame. The equipmentexploits these two units of information to recalculate the data providedby the mobile unit in the fixed reference frame.

[0026] The fixed unit comprises means for determining the coordinates ofthe mobile unit in the fixed reference frame R_(c), as well as adatabase in which are recorded a series of data comprising at least, foreach acquisition a₁, the measured distance D(a₁), the orientation O(a₁)of the mobile unit at the moment of the acquisition and the coordinatesC(a₁) of the mobile unit.

[0027] The equipment advantageously comprises at least two sensorsintegral with the fixed reference frame R_(c) transmitting an electricsignal which is a function of the position of the reference frame of themobile unit in the fixed reference frame R_(c).

[0028] The mobile unit advantageously has at least one radio-frequencyreceiver, with the equipment comprising means for localization of thetransmitter in the fixed reference frame.

[0029] According to one preferred mode of implementation, the telemetrichead comprises one or more lasers, at least one of which emits visibleradiation. According to a variant for mapping irregular volumescomprising partial partitions, the process comprises a step of placingthe fixed equipment in a part common to two adjacent volumes. Accordingto another variant, the process comprises a step consisting of placing amarker in a part common to two adjacent volumes and of performing theacquisition of at least one point of this marker from a first space forrecording the coordinates C₁(P_(c)) of this point in relation to aspecific reference frame R₁ of the first space, of recording thecoordinates of this same point by acquisition from a second space forrecording the coordinates C₂(P_(c)) in the reference frame R₂ and ofcalculating a transformation matrix such that the transform of C₁(P_(c))corresponds to C₂(P_(c)) for the purpose of enabling the fusion of thebase B₁ of the points acquired in the first space and the transformationof the base B₂ of the points acquired in the second space.

[0030] According to another variant, the process comprises a step ofrecording at least one element common to two separate spaces, ofrecording a first base B₁ of coordinates of the points of acquisition ofthe first space in relation to a specific reference frame R₁ of thefirst space, this base B₁ comprising the coordinates C₁(P_(c)) in thereference frame R₁ of at least one common point P_(c), of recording asecond base B₂ of coordinates of the acquisition points of the secondspace in relation to a specific reference frame R₁ of the second spaceR₂, this base B₂ comprising the coordinates C₂(P_(c)) of the commonpoint P_(c) in the reference frame R₂ and of applying to one of thebases a transformation matrix such that the transform of C₁(P_(c))corresponds to C₂(P_(c)) for the purpose of allowing the fusion of baseB₁ and the transformation of base B₂.

[0031] Turning now to the drawings generally, the equipment according tothe invention comprises:

[0032] a portable plotting tool (1) comprising a telemeter with manualscanning;

[0033] a case (2) comprising a portable computer (5), a dual batterypower system and a positioning system; and

[0034] an electronic unit (7) equipped with a display screen (8)attached to the operator's belt.

[0035] The telemeter is in the form of a portable plotting tool (1)whose position and plotting direction are determined by a fixed device(2). The laser telemeter (using elapsed time, frequency scanning, phasescanning or frequency beating) measures the distance of the targetedobject.

[0036] A calculator (5) is controlled by a computer program thatprovides for functions such as: reconstruction of simple surfaces andtheir assembly in a quasi-automatic manner, fusion of objects with anarchitecture type interface program to provide 2D/3D plans andcompatible files of the AutoCAD type (trade name). The equipmentoptionally comprises a so-called “high head projection.”

[0037] The portable plotting tool (1) has a handle (6) supporting alaser telemeter (3) and a positioning system (4). The unit (7) may beconnected to:

[0038] the portable plotting tool (1) by an optical fiber; and

[0039] the case (2) by a wire system, by radio communication or thelike.

[0040] The laser is a visible laser of class 2 (ocular safety) having anacquisition speed of about 100 Hz and a measurement precision on theorder of about a millimeter. The range is between about 0.1 and about 10m, with additional ranges, for example, about 10-about 20 m or about20-about 30 m.

[0041] The system (4) for positioning and orientation in space comprisesone or more magnetic sensors. An error in the quality of the magneticfield (field curvature) can be detected by using two sensors. In thevariant comprising two magnetic sensors, integrated in the handle, forexample, it is possible to permanently calculate the distance separatingthem (from the measurements made) and compare the distance calculatedfrom the signals emitted by the two sensors with the real distancedetermined in the factory. A comparison circuit emits a signal if thedifference between the measured distance and the calculated distanceexceeds a predetermined threshold value.

[0042] The same operation can be implemented by comparing the values ofangles produced by each magnetic sensor in a manner to set off an alarmin the case of discordance between the two sensors. It is also possibleto employ the reading of the positions of each sensor for recalculatingthe plotting direction. In the case of an alarm, the operator canrecommence his measurements either by coming closer to the antenna ordistancing himself from a close metallic mass.

[0043] The positioning system provides information on the positioningand orientation of the telemeter by a measurement in relation to anotherreference frame. The positioning method is either based on a magnetic oracoustic technique from a transmitting antenna or based on a radio oroptical wave technique by triangulation from multiple beacons emittingdifferent frequencies. This measurement system provides the position andorientation of the reference frame linked to T in relation to theantenna point A.

[0044] It is possible to determine the spatial coordinates of O inrelation to A by means of a computer program. The program also makes itpossible to process clouds of points in a manner to extract the planeposition or other more complex objects (column, molding and the like).Object fusion techniques make it possible to reconstitute the totalityof an apartment building.

[0045] Use of the equipment according to the invention is describedbelow with reference to FIG. 2. The user enters a room with the tool,places the case more or less in the middle of the room on a table or onthe floor. The user then opens the case and starts up the computer. Theuser then initializes a sequence indicating to the computer that theuser is beginning the acquisition of a new room. The user plots theposition of a wall by scanning it with the visible laser beam: a buttonon the handle allows the user to indicate to the computer when to recordthe measurements. The user then plots the laser beam successively on allof the walls, the ceiling, floor, columns and the like. The userverifies the work in real time by observing the room be automaticallydrawn on the screen preferably carried on a belt.

[0046] The user indicates to the computer by clicking on thecorresponding icon the type of object to measure and the position in theroom (door, window, socket, baseboard or the like). Then the user canplot certain zones on which the user wants to emphasize fine details(borders, reliefs, moldings, frames and the like). The user furthermoreplots on the screen the object(s) common to two measurements ofsuccessive rooms (door, wall and the like), thereby enabling thesubsequent fusion of the rooms. The user then records other informationstemming from other measurement means (tape measure, caliper rule) andpossibly enters other information: the condition of the surfaces, thenumber of offices, closets and the like. In the case of hidden parts,the user measures the room under a different angle and fuses themeasured room with the project in progress.

[0047] The equipment according to the invention can also be used toperform an exterior plotting (facade plotting). Similarly, it can beused in certain industrial applications: plotting forms for qualitycontrol and other applications.

[0048] Once the device has plotted the position of a point with theprecision associated with it, the software program can calculate thebest plane (or the best cylinder for a column) passing through thesepoints. Because of the nature of the measurement, the higher the numberof points, the better is the precision on the position of the plane. Itvaries with {square root}N if N is the number of measurements for aplane. The precision on the position of an angle is, thus, directlylinked to {square root}N.

[0049] If, for example, the measurement system plots 100 points of aplane with a precision of 1 cm, the position of this plane will thus beknown with a precision of 1 cm/{square root}100=1 mm. The precision ofthe position of the angle of the wall (even if it is partially hidden)will be 1 mm.

[0050] The telemetry process according to the invention requiresmeasuring a certain number of points per room which can be listed asfollows:

[0051] at least ten points per plane;

[0052] two points for a door (diagonal); and

[0053] two points for a window (diagonal).

[0054] The doors should be calibrated at the beginning. The usermeasures precisely a (or the) typical door(s) of the building such thatthey can subsequently be situated solely by their diagonal. The same istrue, e.g., for the windows or columns.

[0055]FIG. 3 represents a variant of implementation for mappingirregular spaces comprising volumes partially separated by partitions. Amarker (10) is placed in a part common to two spaces separated by apartition (11). One then performs the acquisition of the pointcoordinates of this marker from a first space and then from a secondspace. The acquisition data is recorded in two distinct bases containingmoreover the data relative to the acquisitions in the correspondingspace.

[0056] The fusion of these two bases can be implemented afterrecalibration of the bases by application of a transformation matrixdetermined with the coordinates of the points of the markers recoveredafter application of the transformation matrix. This allows mapping ofvolumes comprising zones that are not visible from a common point.

[0057]FIG. 4 illustrates another method consisting of performing theacquisition of several common points (12, 13) (for example, doors,windows or walls) or pairs of elements the relative position of which isknown. One then performs the mapping of the two volumes (15, 16)separated by a partition (17). A transformation matrix is thencalculated to enable fusion of the two cartographic bases.

[0058] This invention has been described above as a nonlimitativeexample. One of ordinary skill in the art will be able to proposediverse variants without departing from the framework or scope of theinvention as defined in the appended claims.

1. Telemetry equipment for two-dimensional or three-dimensional mapping of a space comprising: a movable telemetry head comprising a first sensor for measuring a distance to a target within the space and a second sensor for measuring a distance to a third sensor; and a fixed unit for acquiring the position of the telemetry head in a fixed reference frame within the space, the fixed unit comprising the third sensor which performs the measurement of the distance between the second sensor and the third sensor.
 2. The telemetry equipment according to claim 1, the fixed unit comprises means for determining coordinates of the telemetry head in the fixed reference frame and a database in which are recorded a series of data comprising at least, for each acquisition a₁, a measured distance D(a₁), an orientation O(a₁) of the telemetry head at a moment of acquisition and coordinates C(a₁) of the telemetry head.
 3. The telemetry equipment according to claim 1, wherein the fixed unit further comprises a sensor which emits an electric signal which is a function of the position of the fixed unit in the fixed reference frame.
 4. The telemetry equipment according to claim 1, wherein the third sensor transmits 3 coordinates and 3 angles.
 5. The telemetry equipment according to claim 1, wherein the second sensor comprises means for generating an alarm signal in the case of drift.
 6. The telemetry equipment according to claim 1, wherein the telemetry head has at least one radio-frequency transmitter and means for localization of the transmitter in the fixed reference frame.
 7. The telemetry equipment according to claim 1, wherein the telemetry head comprises at least one laser emitting visible radiation.
 8. The telemetry equipment according to claim 1, wherein the fixed unit further comprises a memory containing a library of objects.
 9. A telemetry process for two-dimensional or three-dimensional mapping of a space comprising: remotely acquiring a position and orientation of a laser telemeter (portable unit) in a fixed reference frame of a fixed unit within the space by manual plotting with a portable tool comprising a sensor emitting a visible laser beam, and measuring the distance between the telemeter and the fixed unit.
 10. The telemetry process according to claim 9, further comprising calculating in real time an image from acquisition points to allow verification of plotting.
 11. The telemetry process according to claim 9, further comprising plotting selected points of more precise reference positioning or certain zones of fine details.
 12. The telemetry process according to claim 9, further comprising inputting information into the fixed unit generated from another measuring means.
 13. The telemetry process according to claim 9, further comprising placing the fixed unit in a location common to two adjacent spaces.
 14. The telemetry process according to claim 9, further comprising: placing a marker in a location common to two adjacent spaces, performing the acquisition of at least one point of the marker from a first space for recording coordinates C₁(P_(c)) in relation to a specific reference frame R₁ of the first space, recording coordinates of the same point by acquisition from a second space for recording coordinates C₂(P_(c)) in a reference frame R₂, and calculating a transformation matrix such that the transform of C₁(P_(c)) corresponds to C₂(P_(c)) for the purpose of enabling fusion of base B₁ of points acquired in the first space and the transformation of base B₂ of points acquired in the second space.
 15. The telemetry process according to claim 9, further comprising: recording at least one element common to two separate spaces, recording a first base B₁ of coordinates of points of acquisition of the first space in relation to a specific reference frame R₁ of the first space, wherein base B₁ comprises coordinates C₁(P_(c)) in the reference frame R₁ of at least one common point P_(c), recording a second base B₂ of coordinates of acquisition points of the second space in relation to a specific reference frame R₁ of the second space R₂, wherein base B₂ comprises coordinates C₂(P_(c)) of the common point P_(c) in the reference frame R₂, and applying to one of the bases a transformation matrix such that transform of C₁(P_(c)) corresponds to C₂(P_(c)) to permit fusion of base B₁ and transformation of base B₂.
 16. Telemetry equipment for the two-dimensional or three-dimensional mapping of a volume, said equipment comprising a telemetry head and a means for acquiring the position of said measurement head in a fixed reference frame, the equipment being constituted by an autonomous portable unit comprising a telemetry head and a fixed unit, the two units comprising means for remote acquisition of the position and orientation of the portable unit in said fixed reference frame, characterized in that it comprises at least two sensors, a first sensor measuring a distance, a second sensor measuring a position and a direction; a third sensor performing the measurement of the distance between sensor and sensor. 